A custom short code is a short code that a developer wants to associate with their application that is different from the default 8-digit short code provided by the AT&T API Platform.
If the custom short code is, as is common, a 5-digit or a 6-digit short code that is managed by usshortcodes.com to be used for cross-carrier messaging, it must be leased by the developer from usshortcodes.com and the developer must provide proof to AT&T that they own the short code before it can be associated with their application on the AT&T API Platform.
If the custom short code being requested by the developer is not a 5-digit or 6-digit short code, then AT&T determines whether the code is available, and whether it is willing to associate that short code to the application. If AT&T approves the custom short code for the given application, the application may incur additional charges.
There are two types of short codes that may be assigned to your application:
- Online short code: This short code is assigned to your application by default. It is also assigned if you provide a listener URL for Mobile Originated SMS messages so that you get notifications in real time.
- Offline short code: This short code is assigned if you are polling for messages or if you did not provide a listener URL for the incoming Mobile Originated SMS messages.